Parameters of a bottom-hole area are determined during non-stationary operation of a well based on the obtained temperature data of inflows, which, in turn, can be obtained as with known devices, and by means of the device described in this invention.
Thus, the non-stationary operation of the well takes place during starting a well after a long period of inactivity, change of well production, i.e. during situations where temperature of the inflow (s) varies in time.
It is known that one of quantitative characterizing parameters for a bottom-hole area is a well skin factor (S)—a hydrodynamic parameter characterizing an additional filtration resistance to a fluid inflow in the bottom-hole area resulting in reduced production rate as compared with a perfect (ideal) well. The reasons for the additional resistance is a hydrodynamic imperfection of the formation exposing, the bottom-hole area pollution as well as non-linear effects related to high fluid flow velocities in the bottom-hole area porous medium.
Thus, if the skin-factor is close to zero (including the determination error: −1<S<1), a near-wellbore area is considered unchanged and a well-ideal. The skin-factor large positive value S>1 is an evidence of the near-wellbore area pollution as well as the well imperfection which requires additional influx improvement activities (additional perforation, formation hydraulic fracturing etc.). The skin-factor significant negative value S<−1 is observed in case of an increased permeability of the near-wellbore area (cracks, caverns etc.).
Currently well hydrodynamic research methods are known (Buzinov S. N., Umrikhin I. D., Issledovanie neftyanyx i gazovyx skva{hacek over (z)}in I plastov. Moscow, Nedra, 1984 (Survey of Oil and Gas Wells and Formations), enabling determination of skin-factor (among other parameters). However, these methods normally determine average skin-factor value for several operating producing wells simultaneously and do not enable determination of factors setting this skin-factor value, i.e. evaluation of perforation zone parameters and parameters of the bottom-hole area.
On the other hand, from the prior art it is known (see: Chekalyuk E. V., Termodinamika neftyanogo plasta., Moscow, Nedra, 1965, p. 238 (Oil Formation Thermodynamics)) that a temperature of a fluid flowing from a reservoir into a well even from an originally isothermal reservoir varies as a function of time (in technical literature this effect is called a transient Joule-Thomson effect). Data on inflow temperature variations as function of time may be used to determine parameters of a damaged reduced-permeability bottom-hole area (see: Yu. A. Popov, V. P. Pimenov, V. V. Tertychnyi, Developments of Geothermal Investigations of Oil and Gas Fields, Oilfield review, spring 2001, pp. 4-11).
However, this information practically cannot be derived from the inflow data acquired by a wellbore logging. Besides, the theory given in Chekalyuk E. V., Termodinamika neftyanogo plasta., Moscow, Nedra, 1965, p. 238 is true only for a cylindrically symmetrical flow and cannot be used directly for a complex spatial fluid flow structure in a perforation zone.